Safety Hood, Traffic Light. Morgan's first well-known invention was the safety hood, a forerunner of the gas mask. When 32 workers in Cleveland, Ohio, were trapped during a tunnel collapse in 1916, Morgan and several volunteers using the masks were able to reach the trapped men and rescue several survivors. In 1923, Morgan patented his best-known invention, the three-way traffic signal, based on signs that signaled stop and go. He sold his patent rights to General Electric, which developed an electrical version.